Ecology 1 Study Guide

Justin Huang, David Uchime

1. Ecology is the study of how abiotic and biotic affect life around the world (orsimply the study of the relationships among organisms and theirenvironment).
2. Ecological levels of organization

1. Organism: one member of a species (ex. One frog).
2. Population. A group of members of the same species (ex. A pack ofwolves)
3. Community: all of the organisms in one area (ex. A forest communityof deer trees, squirrels, foxes, and fungi).
4. Ecosystem: all biotic and abiotic factors of an area. (ex.Grasslands ecosystem including soil, rain, bison, deer, elephants, etc.)
5. Biome: a type of ecosystem (ex. tundra biome)
6. Biosphere: all of the ecosystems located around the world (allliving and nonliving factors on earth).

3. The ways ecologist conduct research:

1. Observation: the act of carefully watching something over time.Observations of populations are often done by a visual survey.
2. Experimentation is the act of conducting a test in a lab or afield.

1. Lab experiments give the researchers more control but are not asreflective of the complex interactions of nature
2. Field experiments give a more accurate depiction of nature but maynot be able to determine actual cause or effect.

3. Modeling is the practice of making hypothetical situations usingreal data from a species.

1. ​​Modeling allowsscientists to learn about organisms or ecosystems in ways that would not be possible in a natural or labsetting.

4. Biotic factors are the living parts of an ecosystem (plants,animals, fungi, etc.) while abiotic factors are the nonliving parts of an ecosystem (sunlight, water,rocks, etc.)
5. Biodiversity is the variety of life in an ecosystem.

1. Changes in one factor of an ecosystem can change other factors of anecosystem due to

1. Predator-prey relationships (ex. A lack of sea urchins causing kelpto grow uncontrollably)
2. Symbiotic relationships (ex. If kelp populations reduce, all theorganisms that rely on kelp to survive will die).

6. Keystone species are species that have an usually large effect on anecosystem, (ex. Beavers build dams that give many other species homes, therefore they are a keystonespecies).
7. Autotrophs (or producers) are organisms that make their own food. heterotrophs(or consumers) are organisms that eat other organisms for food.
8. The two processes that are used by producers to create food arephotosynthesis and chemosynthesis

1. Photosynthesis is the process of using energy from the sun to createfood (used by plants
2. Chemosynthesis is the process of using energy from specificchemicals to create food.

9. Energy in an ecosystem starts from the sun, goes to the plants, andis then passed on from consumer to consumer until the tertiary consumers have the energy (the energygoes through each trophic level).

1. About ten percent of the energy is passed on from one trophic levelto the next.
2. Lower trophic levels are generally bigger so that they can supportthe higher levels (ex. More ants than wolves)

10. Roles of organisms in a food chain/ Food web

1. Producers: make their own food, generally near the beginning of thefood chain (plants)
2. Consumers: eat other organisms

1. Primary consumers eat only plants (herbivores)
2. Secondary consumers eat animals (carnivores)
3. Omnivores eat plants and animals (racoons, humans).
4. Detritivores eat dead organic matter

1. Decomposers are detritivores that break down dead organic matterinto simpler compounds.

11. The food eaten by an organism is broken down and is used tosupply it with the energy that it needs in order to survive and reproduce.
12. “Be prepared to calculate energy transferand efficiency in organisms” (just remember the ten percent rule which is that ten percent of theenergy is passed between trophic levels) .

1. Also remember that the ten percent rule is a general rule and may not beapplicable to all ecosystems.

13. Specialists vs. Generalists

1. Specialists are organisms that eat one organism or a very smallgroup of organisms (ex. Monarch caterpillars).
2. Generalists are organisms that eat a variety of organisms (Racoon,Cockroaches, Humans).

14. Matter cannot be created or destroyed, so nutrients likewater, nitrogen and carbon must be recycled so that we don’t run out of them.
15. The water cycle. (Hydrologic)

1. The Sun is the driving force of the water cycle
2. The first step of the water cycle is that the sun heats the earthand causes the water to evaporate (evaporation)

1. Transpiration is the evaporation of water through plants

3. Once the water vapor has risens, it cools and condenses back intoliquid water. (condensation)
4. After the water has condensed, it returns to the earth asrain, sleet, snow or hail (precipitation).
5. After the water has returned to the surface of the earth, it flowsuntil it reaches a large body of water (runoff)

1. Surface runoff is when water flows on the surface of the earth to alarge body of water like a ocean
2. Seepage is when water goes through the surface of the earth and goesto groundwater.

16. Oxygen Cycle

1. The two many drivers of the oxygen cycle are respiration andphotosynthesis.
2. oxygen cycles independently through an ecosystem through the cyclingof other organisms
3. Main steps of oxygen cycle

1. Respiration takes in oxygen and turns it into carbon dioxide
2. Photosynthesis takes in carbon dioxide and turns it intooxygen.

17. Carbon cycle

1. Carbon is the building block of all life
2. The carbon cycle moves carbon from the atmosphere through the foodweb, and back into the atmosphere
3. Main source of carbon is fossil fuels
4. The Human activity that has affect the carbon cycle the most is theburning of fossil fuels (combustion)

1. Carbon dioxide is used in photosynthesis where it becomes organicmatter and part of the plant
2. These plants are eaten by consumers who receive that carbon.
3. When plants and animals die, decomposers break down the organicmatter and turn it into fossil fuels
4. When animals perform respiration they release carbon dioxide intothe atmosphere as carbon dioxide
5. When fossil fuels are burned, carbon is released back into theatmosphere as carbon dioxide.
6. Carbon is also stored in oceans and water plants and animals recyclethe carbon dioxide through respiration and photosynthesis.

18. Nitrogen travels through the environment in many ways, movingthrough the atmosphere and through the soil. The nitrogen cycle is the cycle that starts withatmospheric nitrogen, changes it into usable nitrates for plants, which travels back into the soil afterdecay, and changes back into atmospheric nitrogen through denitrification.

1. Bacteria in the nitrogen cycle are essential to the cycle.

1. Rhizobium is a bacteria that changes atmospheric nitrogen (N2) into NH3 (Ammonia)
2. Nitrification Bacteria changes NH3 (Ammonia) into NO3 (Nitrates)
3. Denitrifying Bacteria change NO3 (Nitrates) into N2 (Atmospheric Nitrogen)

2. Ammonification, Nitrogen-fixation, and Denitrification

1. Ammonification occurs when a plant or animal dies (or releases waste). OrganicNitrogen is converted back into Ammonia (NH3)
2. Nitrogen Fixation is the process of turning nitrogen gas (N2) into nitrates (NO3)
3. Denitrification is the process by which nitrates (NO3) are turned back into nitrogen gas (N2)

3. The usable form of nitrogen for plants is in the form of nitrates(NO3)
4. Human activities that can disrupt the nitrogen cycle include makingfertilizers, burning fossil fuels, air pollution, etc.

1. Consequences:

1. Eutrophication (nitrogen dissolves in water, stimulates growth ofplants and algae, which leads to an excess of bacteria to decompose these plants an animals, leading toa shortage of oxygen)
2. Acid Rain (pH levels of soil and water is altered, which causes the death ofplants and animals)

19. Three types of pyramid models

1. Energy Pyramid: shows the distribution of energy among trophiclevels

1. Only 10% of the energy at each tier is transferred from one trophiclevel to another
2. Can NEVER be inverted (there can’t be more energy at the topthan bottom)

2. Biomass Pyramid: shows the distribution of biomass in anecosystem

1. Measures the total dry mass in a given area
2. CAN be inverted in aquatic ecosystems (if algae or other organismsreproduce fast enough)

3. Pyramid of Numbers

1. Measures the number of individual organisms at each trophic level inan ecosystem
2. CAN be inverted (ex. one tree can support 10 squirrels (idk actuallybut that was an example lol))

20. 10% of energy at each level is passed on to the next level (makesure you know this because calculations will be on the test)
21. The three parts of an ecological niche are food, abiotic conditions,and behavior

1. Ecological niche: all the factor that a species needs to survive,stay healthy, and reproduce
2. A niche differs from a habitat in the way that it includes theirbehavior and other factors not defined as part of the habitat

22. The competitive exclusion principle states that two species cannotboth survive very long if they share the same ecological niche.

1. Possible outcome: one life form may drive out the other

23. Interactions among organisms:

1. Predation: when an organism captures and eats anotherorganism

1. Ex. snake eats mouse

2. Symbiosis: when two organisms live together

1. Mutualism: both organisms benefit from the presence of twospecies

1. Ex. clownfish + anemone

2. Commensalism: one organism benefits while the other one isunharmed

1. Ex. remora fish + shark

3. Parasitism: one organism benefits while the other organism isharmed

1. Ex. lice + human head

3. Competition

1. The rivalry between or among living things for territory, resources,goods, mates, etc.

24. Population density: the number of individuals in a definedarea

1. Calculated by the formula

25. Types of population dispersion

1. Clumped distribution: organisms living in close proximity to eachother
2. Uniform distribution: organisms living in uniform proximity to eachother
3. Random distribution: organisms living in random places in anenvironment

26. Shapes of curves:

1. Exponential growth curve: shaped like a “J”
   

1. Equation shown above:

2. Logistic growth curve: shaped like an “S”
   

1. Equation shown above:

27. The carrying capacity affects the size of a population by settingthe limit to how big the population can grow to (horizontal asymptote)
28. Density-dependent and independent factors

1. Density-dependent factors: factors affected by the number ofindividuals in a given area

1. Ex. predation, competition, disease

2. Density-independent factors: factors that are not affected bypopulation density

1. Ex. weather events, human activities

29. Ecological succession: the process where new species inhabit anarea
30. Primary succession is where the new land iscompletely new, which can occur after the cooling of lava, or when a glacier moves and uncovers rockswithout soil, basically starting from scratch. It takes a lot more time for succession to occur than forsecondary succession, which is when soil and nutrients arepresent in an environment and succession occurs.
31. Catastrophic events that could lead to secondary succession includewildfires, flooding, and human activities (deforestation)
32. Ecological succession increases the number of species in a livingarea, therefore, it increases biodiversity
33. The change in the environment can impact the ecosystem byoverwhelming the carrying capacity of ecosystems, which is something that climate change can do.Temperature variation can cause a change in interactions among species of an ecosystem.
34. Invasive species can completely demolish an ecosystem by taking upall of the resources and beating out the competition because of reasons such as not having a predator orhaving a fast reproductive time
35. Cane toads were brought to Australia to contain the problem of beetles eatingthe Sugar Cane crops in Australia. They completely rolled theenvironment and had an exponential growth because they had no predators in the area.

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